Three-dimensional shape measurement plays an essential role in numerous fields, including, but not limited to, manufacturing, medicine, security, and entertainment. Among various available 3D scanning techniques, there is a range of single-shot techniques with projection of elaborate space-coded patterns, which are suitable for 3D measurement in time critical conditions. The well-known Kinect® depth camera belongs to this category. (The Kinect® depth camera was developed by PrimeSense and purchased by Microsoft Corporation, Redmond, Wash.) Kinect® projects an infrared speckle pattern (i.e., a scattered dot pattern) that is highly random and thus provides enough distinguishability for detecting the pattern deformation in space. However, any form of space coding implies local depth smoothness and neighborhood dependency during decoding, which inevitably leads to loss of accuracy and data density.
In contrast, phase shifting profilometry (PSP) with fringe projection is widely adopted due to its high accuracy and high data density. Generally, PSP is suitable for static measurement as it requires multiple patterns to be projected sequentially. For the most commonly used sinusoidal fringe, at least three images are needed to generate a phase map. Moreover, due to the periodicity of the sinusoidal signal, the obtained phase map is wrapped. To recover the absolute phase for unambiguous 3D measurement of complex scenes, the actual image acquisition number is usually much larger than three. The advancement of camera and projector technology has enabled fast and accurate 3D scanning with PSP. Further acceleration of the measurement process may be obtained by reducing the image acquisition number for absolute phase recovery.